2-ways accuton bookshelf

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kevinlin1013

Member
2004-08-15 8:15 pm
Taipei
  • #1
    I am ready to DIY a 2-ways bookshelf based on accuton drivers. I have ordered a pair of C158-8-085 mid-woofer but it seems there is very rare discussion of this driver for DIY.

    The tweeter is considerated to use accuton C25 or C30 , Can I get some suggeston? If I want to cross at 2.5K for second-order , Does it a little over load for the C25?

    If considering the Scan-Speak tweeter like ScanSpeak R2904/7000 , D2904/7100 , R3004/6620-00 , D3004-6620.....Will it get better proformance?

    Asking for some suggestion for the driver selecting and cross-over point recommendation.

    Thanks for everybody's help!
     
    C

    crazyhub

    Member
    2005-11-20 10:41 pm
    alsace
  • #2
    The main cone break-up of the C158 is near 4.1khz; a third harmonic distortion occurs near 1.4khz; so I would try to cross the two drivers in this area. Obviously the x-max of a C30 should better suit this Fx than a C25.
    IMHO, SS tweeters or Accuton ones aren't a matter of performance but a matter of taste.
     
    K

    kevinlin1013

    Member
    2004-08-15 8:15 pm
    Taipei
  • #3
    crazyhub said:
    The main cone break-up of the C158 is near 4.1khz; a third harmonic distortion occurs near 1.4khz; so I would try to cross the two drivers in this area. Obviously the x-max of a C30 should better suit this Fx than a C25.
    IMHO, SS tweeters or Accuton ones aren't a matter of performance but a matter of taste.
    Click to expand...

    Thank for your information. I have contacted the local driver dealer , they said:"It is very dangerous to crossover the ceramic tweeter below 3KHz by 2nd-order filter."

    Is it real? Did someone have the experiment of the ceramic tweeter? Thanks !
     
    C

    crazyhub

    Member
    2005-11-20 10:41 pm
    alsace
  • #5
    A C30-6-023 has a linear excursion of +/- 1.1mm, a Fs of 570hz, is ferrofluid filled, is rated 120w power handling; Accuton recommand to cut it over 1800hz, saying nothing about the slope.
    Regarding its x-max of 1.1mm, its Sd of 8.55cm² and impedance of 7.5 ohms at 1.5khz, it should theorically be able to give 109dbs / 1meter into free space (add 6dbs into half-space) at 1.5khz just before reaching its x-max. So 97dbs at 750hz (-12dbs), 85dbs at 375hz (-12dbs).
    So this driver can theorically be cuted second order acoustic at 1.5khz if you project to use it half-space at max 115dbs / 1m; or still 2nd order at 2khz at max 120dbs; or still 2nd order at 2.5khz at max 124dbs. All these data are x-max related, not power compression. Nevertheless you see that the statement "It is very dangerous to crossover the ceramic tweeter below 3KHz by 2nd-order filter." isn't right in this case.
    In its Humble Statement Tony Gee crosses a C30N-6-24 over at 2khz 12db/oct without any problem:
    Humble Homemade Hifi
    ;)
     
    K

    kevinlin1013

    Member
    2004-08-15 8:15 pm
    Taipei
  • #6
    Godzilla said:
    lol about experimenting on such an expensive tweeter.

    the accuton speakers i heard at shows in NYC all sounded really good.
    Click to expand...

    It's really expensive drivers. :(
    I really love the sound provided by the ceramic driver. I have heard Avalon/Lumenwhite/Marten Design/Kharma/Consensus Audio Speakers and love the sound. But they are expensive and too big for me now...

    So I think to begin with a small two-ways monitor is a good idea.
     
    Last edited:
    K

    kevinlin1013

    Member
    2004-08-15 8:15 pm
    Taipei
  • #7
    crazyhub said:
    In its Humble Statement Tony Gee crosses a C30N-6-24 over at 2khz 12db/oct without any problem:
    Humble Homemade Hifi
    ;)
    Click to expand...

    Thanks! Mr.crazyhub for providing such useful information and suggestions.

    It is my first time to design a crossover circuit from the beginning. My previous speaker is Scan-Speak 9500+8545 and just used the circuit from the internet.

    If I want to start with the crossover calculator which impedance should I use? From the chart of the driver to find the frequency that I want to use as crossover-point?
     
    S

    sreten

    R.I.P.
    2003-11-27 8:59 pm
    Brighton UK
  • #8
    kevinlin1013 said:
    Thanks! Mr.crazyhub for providing such useful information and suggestions.

    It is my first time to design a crossover circuit from the beginning. My previous speaker is Scan-Speak 9500+8545 and just used the circuit from the internet.

    If I want to start with the crossover calculator which impedance should I use? From the chart of the driver to find the frequency that I want to use as crossover-point?
    Click to expand...

    Hi,

    Don't even think about using a crossover calculator with such drivers,
    or in fact any decent drivers. You need to do it properly as outlined
    below. You needs published measurements of the drivers.

    FRD Consortium tools guide

    rgds, sreten.

    http://sites.google.com/site/undefinition/diy
    Zaph|Audio
    RJB Audio Projects
    Speaker Design Works
    HTGuide Forum - A Guide to HTguide.com Completed Speaker Designs.
    Humble Homemade Hifi
    Click below to go to
    Quarter Wavelength Loudspeaker Design
    The Frugal-Horns Site -- High Performance, Low Cost DIY Horn Designs
    Linkwitz Lab - Loudspeaker Design
    Music and Design
     
    C

    crazyhub

    Member
    2005-11-20 10:41 pm
    alsace
  • #12
    kevinlin1013 said:
    Thanks for the information and helps!

    If I use a notch filter before the mid-woofer for dealing with the cone-breakup , Should I change the value of the capacitors/inductors(Crossover circuit) just because of the impedance it loads has been changed?(Because added the Notch filter)
    Click to expand...

    If correctly implemented the notch does little below the break-up frequency; so you may have not to modify the circuit; this being said don't hope to create something good without measurements, at least in an acceptable time; read this for example, particullarly example#1; see the relative complexity of Troel's filter vs the bad one:
    crossovers
     
    K

    kevinlin1013

    Member
    2004-08-15 8:15 pm
    Taipei
  • #14
    crazyhub said:
    If correctly implemented the notch does little below the break-up frequency; so you may have not to modify the circuit; this being said don't hope to create something good without measurements, at least in an acceptable time; read this for example, particullarly example#1; see the relative complexity of Troel's filter vs the bad one:
    crossovers
    Click to expand...


    Thanks for reply. I have already read Troel's site , very useful information.

    According to the datasheet of C158 , Re=7.8ohm , Inductance of coil=0.54mh

    So if I choose R=10ohm and C=5.68uf for the Zobel circuit , is the value suitable for it?
     
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